Re: [iio:testing 40/43] ld.lld: error: undefined symbol: __udivdi3

[Jarkko Nikula]

On 9/14/21 4:52 PM, William Breathitt Gray wrote:
> On Tue, Sep 14, 2021 at 01:41:03PM +0100, Jonathan Cameron wrote:
> > On Sun, 12 Sep 2021 06:43:58 +0800
> > kernel test robot <lkp@xxxxxxxxx> wrote:
> >
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git testing
> > > head:   77a4a019161bcba51af1dbbeadc04795840fb3e0
> > > commit: f7da4339ca510e4476ea35cb9fd44f3f190706c5 [40/43] counter: Internalize sysfs interface code
> > > config: i386-randconfig-r022-20210911 (attached as .config)
> > > compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 261cbe98c38f8c1ee1a482fe76511110e790f58a)
> > > reproduce (this is a W=1 build):
> > >          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> > >          chmod +x ~/bin/make.cross
> > >          # https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/?id=f7da4339ca510e4476ea35cb9fd44f3f190706c5
> > >          git remote add iio https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
> > >          git fetch --no-tags iio testing
> > >          git checkout f7da4339ca510e4476ea35cb9fd44f3f190706c5
> > >          # save the attached .config to linux build tree
> > >          mkdir build_dir
> > >          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir ARCH=i386 SHELL=/bin/bash
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > >
> > > All errors (new ones prefixed by >>):
> > >
> > > > > ld.lld: error: undefined symbol: __udivdi3
> > >     >>> referenced by intel-qep.c:290 (drivers/counter/intel-qep.c:290)
> > >     >>>               counter/intel-qep.o:(intel_qep_spike_filter_ns_write) in archive drivers/built-in.a
> > This is a result of a change to passing in a u64 instead of a string.   I've applied a fix
> > that uses do_div() and pushed out as testing again.
> >
> > William, please sanity check that fix looks right to you.
> >
> > Thanks,
> >
> > Jonathan
>
> Your do_div() change seems sane to me; would div_u64_rem() work here as
> well, or is do_div preferred because we're not using the remainder?
>
> I'm CCing Jarkko Nikula as well to keep them in the loop.
Yeah I believe do_div() is the right fix for the "counter: Internalize 
sysfs interface code" since the calculation remains the same.

I realized now the filter length has been rounded down. E.g. values 
20-29 from user space set 20 ns long filter in HW. Perhaps better would 
be to round up or to nearest but that goes to some future patch if needed.

Jarkko